Beyond starvation: An update on the autophagic machinery and its functions

Autophagy was originally identified as a cytoprotective system that provides emergency backup energy and basic building blocks under starvation condition by digesting self components. Recent advances in the field unveiled that this system also protects cells against multiple types of stress, as well as invasion by pathogens. Consistent with these findings, autophagy has been redefined as a safeguard system that plays a vital role in human pathology, and this realization has led to exponential progress in autophagy research. In this review, we introduce the basic mechanisms of canonical autophagy and also discuss selective autophagy, a set of pathways that target specific cellular components for digestion; in particular, we focus on lysophagy, a recently identified mechanism required for lysosomal homeostasis.